A field-effect transition device consists of a thin glass cell filled with a 10-20 .mu.m layer of nematic liquid crystals. The inner walls of the cell are coated with an electroconductive material and treated so as to impart a specific spatial orientation to the liquid crystal molecules. As a result of this molecular orientation, the cell has the property of rotating the plane of vibration of linearly polarized light by ninety degrees. During the application of an electric field between the cell walls this optical property is reversibly destroyed and linearly polarized light is transmitted by the cell without rotation. Thus, if the cell is placed between crossed polarizers, it will transmit light when the electric field is off and extinguish it when the field is on. By choice of the electrode pattern and by selective application of the electric field, any dark-light display may be obtained. Devices which may make use of this display include time-keeping devices such as wrist watches, clocks and timers; technical instruments such as laboratory equipment, and hand calculators; and alphanumeric displays such as remote computer read-outs, scoreboards, visual paging system, etc.
The field-effect transition display may be used in a transmissive mode or in a reflective mode. In the reflective mode the reflector should ideally be diffusely reflecting with a directional preference in a plane perpendicular to the plane of the device and parallel to the direction of the digits or letters sought to be displayed. In this mode especially, it is important that the polarizer be as thin as possible and be bonded to the reflector to avoid light losses to surface reflections. Various methods of bonding a polarizer to a reflector and cell were tried including spraying aluminum paint onto the polarizer or evaporating aluminum onto the matte surface, neither method yielding good reflectors; or bonding the polarizer with a pressure-sensitive adhesive, which alters the texture of the aluminum. None of these attempts resulted in significant yields of field-effect transition liquid crystal display cells which are free of cosmetic defects. Yields are low and there is no feasible way of reworking rejects.